In many fields of draughtsmanship and artistry it is often desirable to be able to reassemble two or more sheets in register with one another following the original preparation of one or more of them respectively in register. Thus, for example, in many three-colour processes, so-called three-colour separations are made through different filters and it is required to assemble these in register to see the final image.
With a view to facilitating such activity, various proposals have been made in the past. By way of example attention is directed to U.S. Pat. No. 4,015,034 which discloses an article for applying register or index markers to superimposed sheets or layers in precise registration. When used the article leaves a particular printed configuration on one sheet and a negative thereof on the other. U.S. Pat. No. 4,015,034 discloses a complex multi-layer system for achieving this.
It has now been found that it is possible to produce articles functioning in similar fashion but with much simpler construction requiring only two printing steps which need not be in accurate register one with the other.